Add default "" value to @Launch and improve command line JavaDoc

[loicmathieu]

No description provided.

[quarkus-bot]

Failing Jobs - Building 2c9b6bb

Status	Name	Step	Failures	Logs	Raw logs
✔️	JVM Tests - JDK 11
✖	JVM Tests - JDK 11 Windows	Build	Failures	Logs	Raw logs
✔️	JVM Tests - JDK 17
✔️	JVM Tests - JDK 18

Full information is available in the Build summary check run.

Failures

⚙️ JVM Tests - JDK 11 Windows #

- Failing: extensions/opentelemetry/opentelemetry/deployment 
! Skipped: integration-tests/micrometer-prometheus integration-tests/opentelemetry integration-tests/opentelemetry-grpc and 3 more

📦 extensions/opentelemetry/opentelemetry/deployment

✖ io.quarkus.opentelemetry.deployment.RestClientOpenTelemetryTest.urlWithoutAuthentication line 111 - More details - Source on GitHub

org.opentest4j.AssertionFailedError: expected: <CLIENT> but was: <SERVER>
	at org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:151)
	at org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:132)